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 Post subject: Energized Work Permits
PostPosted: Thu Sep 02, 2010 2:21 pm 
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Location: Yankton SD/ Lead SD
What is the general opinion in regards to having to have an energized work permit in order to replace fuses in a 600 volt, or less, safety switch. I feel that once you have opened the disconnect and verified a zero energy state on the fuse holders, that you do not need a permit but would still need PPE since the line side of the switch is energized. My assumption is based on the condition that the IE level is such that you are not crossing into the prohibited approach boundary to perform the work.


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PostPosted: Thu Sep 02, 2010 4:41 pm 
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cbauer wrote:
What is the general opinion in regards to having to have an energized work permit in order to replace fuses in a 600 volt, or less, safety switch. I feel that once you have opened the disconnect and verified a zero energy state on the fuse holders, that you do not need a permit but would still need PPE since the line side of the switch is energized. My assumption is based on the condition that the IE level is such that you are not crossing into the prohibited approach boundary to perform the work.


Good question but I think an EEWP is still required, but if this is a common task you could use a standing EEWP.


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PostPosted: Fri Sep 03, 2010 10:19 am 
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That is a good question. I would think that a permit would not be required for this work. It would be good to hear what others are doing.


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PostPosted: Tue Sep 07, 2010 12:31 pm 

Joined: Wed Jan 20, 2010 4:08 am
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I would have to agree with the OP. An EEWP should not be required to verify a zero energy state, nor to replace fuses in a deenergized condition. Most disconnects these days have line shields to prevent accidental contact.


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PostPosted: Tue Sep 07, 2010 12:43 pm 
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cbauer wrote:
What is the general opinion in regards to having to have an energized work permit in order to replace fuses in a 600 volt, or less, safety switch. I feel that once you have opened the disconnect and verified a zero energy state on the fuse holders, that you do not need a permit but would still need PPE since the line side of the switch is energized. My assumption is based on the condition that the IE level is such that you are not crossing into the prohibited approach boundary to perform the work.


OK, I see how this can be misread. What is the work you are doing in this switch? If it is anything more than "testing" and you are inside the LAB an EEWP is required if the live parts on the line side of the switch are not "gaurded". Even if they are gaurded, and if you are outside the LAB you may still need arc flash protection.

It also seems you are confused about the PAB and Ei relationship, which is none. PAB is related to shock protection, Ei is a measurement of arc flash energy. Different things.


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PostPosted: Tue Sep 07, 2010 1:25 pm 
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Based on the strict definitions in the 2009 70E, you have "Energized" as electrically connected to, or is, a source of voltage. "Working On (energized electrical circuit parts)" coming in contact with energized circuit parts with body parts or with tools, etc... A zero energy state on the fuse holders cannot by definition be called energized work. The blue commentary section in the 70E Handbook, which is just that a commentary section, entails a person crossing into the Prohibited Approach Zone would constitute working on energized parts. I know this is splitting hairs, but it is somewhat contridictory the way it is presented in the Handbook.


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PostPosted: Tue Sep 07, 2010 3:49 pm 
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Food For Thought - I personally have investigated two incidents where the switch handle was operated to the open position, however, it remained in the closed position. If you are familiar with the old ITE Bulldog bus plug disconnects, there are no true blades it operates more like a breaker and you cannot easily see a closed or open condition when looking at the parts in the switch interior.

IMHO the change of fuses needs a standing work permit.

Taking a tangent, for those of you that are trying to reduce the incident energy in plants that are primarily fusible. If you utilize the Ferraz A6D (or AJT) through 200 amperes and use the A6K (or A4J) from 225 amperes through 600 amperes you will have a HRC of zero over 90% of the time and that is conservative.

I have worked up a reverse approach to applying fuses by dictating the HRC based by a minimum fault current. Once you find the arcing current value where the incident energy exceeds a HRC 0, the incident energy will never be greater for increased fault currents. This does not work for circuit breakers. I have extrapolated a series of points with easy power that defines the HRC for minimum fault currents. If someone is interested i can post the tables.

The above fuses are either UL Class RK1 or UL Class J fuses. The A6K and A4J are non-delay fuses and work extremely well in all cases except for single motor or single transformer circuits. Single transformers are not an issue, on the primary side they should be an RK5 (Ferraz TRS-R) since the worst case scenario on small (less than 600 amperes) dry type tranformers is always the secondary side, those fuses can be the RK1 or J style.

To finish this off, Class RK5 fuses 60 amperes or less should always show less than HRC #0. If you have a circuit that shows greater than a 1.2 cal/sqcm below a 60 ampere RK5 fuse there is something wrong. Either the fault will self extinguish or the voltage regulation is so bad the circuit is unusable.

For those plants that have the fuses earlier then the Class R version, both the Buss FRS and Ferraz TRS K5 fuses, beware. Those fuses exacerbate the incident energy. I just did a study where changing from a early FRS (K5) to a Ferraz A6K-R dropped the incident energy from approximately 30 cal/sq cm to under 1.0 cal/sq cm. Most of the arc flash danger is in the larger fuse sizes and you can tell a pre-Class R by a lack of notches in the blade. Blade style fuses go from 70A through 600A in the Class R family.

The Buss UL counterparts are A6D-R = LPS-R and A6K-R = KTS-R. They should be close. One word of caution, in the greater than 600 amperes product, which is Class L, Buss markets their KRP-C as an equivalent to the Ferraz A4BQ, unless something has changed the arc flash results are substancially lower with the Ferraz A4BQ, especially near the minimum cutoff described above. Ferraz is a $500,000 supporter of the IEEE1584 committee if you wonder why I am using their part numbers.


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PostPosted: Wed Sep 08, 2010 3:57 am 

Joined: Wed Jan 20, 2010 4:08 am
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Flash wrote:
Food For Thought - I personally have investigated two incidents where the switch handle was operated to the open position, however, it remained in the closed position. If you are familiar with the old ITE Bulldog bus plug disconnects, there are no true blades it operates more like a breaker and you cannot easily see a closed or open condition when looking at the parts in the switch interior.

IMHO the change of fuses needs a standing work permit.


This is exactly why you verify that you have a zero energy state with a volt meter. Never, ever rely solely on the position of the disconnect handle. Aside from Flash's excellent example, there may have been a loose connection with the switch blades that caused one or more blades to be welded in the closed position, or even blades that break from the actuating bar.


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PostPosted: Thu Sep 09, 2010 6:00 am 

Joined: Thu Nov 15, 2007 7:58 am
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Location: NY
I've seen a case where the fuse holder was wired backwards . The blades were energizes. When I visit clients I "assume" that the installation was made to code. But, when I open a door and am faced with bare copper, I don't assume anything.

Electrical gear has been around as long as the automobile.
What happened to the old cars ?
They have been junked or see occasional, limited, use .
What about old electrical gear?
It's still energized and getting older every day.


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PostPosted: Thu Sep 09, 2010 6:41 am 
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Location: Yankton SD/ Lead SD
Likewise, I have seen where the lines and loads were reversed on safety switches. This is why a person needs to verify the 'zero energy' state before he begins his work.


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PostPosted: Tue Sep 14, 2010 7:29 am 

Joined: Mon Feb 01, 2010 10:46 am
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flash,

I would be interested in the tables you have if you don't mind posting them..
Jeff


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PostPosted: Mon Sep 20, 2010 6:25 am 
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Location: Lawrenceburg KY
Switch wired backwards

I also have first hand knowledge of safety switches being wired "hot" on the load side and not the line side. A contractor's worker got confused and wired the new service wrong.

Another plant electrical worker went to change phases on the new equipment for rotation on this 480, 60A service in the safety switch and found out the hard way. He did not check or verify. No one was hurt but it could have been bad.

As far as EWP on fuse replacement. As long as safe work practices are followed by a qualifed electrical worker then an EWP may not be required per the specfic companies policy.

IMHO, it depends on who wrote the company policy and if it will be enforced. A qualified electrical worker should maintain the proper PPE and safe work practices.

If your not sure about the quality of workers then I would have a work permit for all the simplist electrical jobs. So it really depends in my mind on several factors that must be considered.


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PostPosted: Fri Oct 22, 2010 5:36 am 
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Capt Jim wrote:
I've seen a case where the fuse holder was wired backwards . The blades were energizes. When I visit clients I "assume" that the installation was made to code. But, when I open a door and am faced with bare copper, I don't assume anything.


Personally, I don't assume it is wired to code. It is a SAD statement to make being an electrician, but I have seen alot of stuff wired wrong. Unless I did the installation myself, I trust nothing that is existing.

On the permit issue... Every client is different, but in order to test for isolation, do you not need a Safe Work Permit for that? After all you are facing the terminals with the door open to check. If something went south, I doubt the client would say "He didn't need a permit.". I believe in "CYA"...


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PostPosted: Fri Oct 22, 2010 6:17 am 
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glen1971 wrote:
Personally, I don't assume it is wired to code. It is a SAD statement to make being an electrician, but I have seen alot of stuff wired wrong. Unless I did the installation myself, I trust nothing that is existing.

On the permit issue... Every client is different, but in order to test for isolation, do you not need a Safe Work Permit for that? After all you are facing the terminals with the door open to check. If something went south, I doubt the client would say "He didn't need a permit.". I believe in "CYA"...


Voltage testing is an exception to an EEWP, however, you still need to wear the PPE.


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PostPosted: Sat Oct 23, 2010 5:14 am 
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Zog wrote:
Voltage testing is an exception to an EEWP, however, you still need to wear the PPE.


In some areas.. I can't open a disconnect, panel, or starter without a Safe Work permit... I am in the oilfield in Alberta...


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 Post subject: Re: Energized Work Permits
PostPosted: Sat May 09, 2015 7:21 pm 

Joined: Tue May 05, 2015 8:31 am
Posts: 3
It's common in AC units for the bottom side of the factory installed breakers to be the line side. IMO this is a hazard that shouldn't be allowed for obvious reasons.


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